This invention concerns a method for the removal of silver contained in an used photographic silver halide developer.
In the photographic industry silver halide films (and papers) are processed after exposure in several treatment baths, in particular at least one developing bath. Such processing methods are well known (see for example Chimie et Physique Photographiques, P. Glafkidxc3xa8s, Vol Chapter XL pages 947-967, 5th edition, 1987). One known problem met in the development of silver halide photographic films is the accumulation metallic silver in the forme of silver-laden slurries in the developing bath. This accumulation of silver-laden slurries results in silver deposits adhering to tank walls, conveyor rollers and all the parts of the processing line. These silver deposits require more frequent maintenance and cleaning operations. Also, the presence of silver-laden slurries in the developing bath reduces the useful life of the developer. Lastly, the silver-laden slurries can be deposited on the processed film, where they form black spots or fogging, which may spoil the developed image.
It is therefore desirable to be able to extract these silver-laden slurries and recover the silver in them. Silver recovery may be economically worthwhile, and is becoming mandatory with the increasingly strict current standards for effluent disposal.
The object of this invention is therefore a method to extract the metallic silver contained in a developer for photographic silver halides, comprising the step of placing the developer in contact with an aluminosilicate polymer having surface organic radicals with functions, selected in the class consisting of SH and xe2x80x94S(CH2)nSxe2x80x94 functions, where n is an integer from 1 to 4 inclusive.
A further object of this invention is a product to extract silver from a photographic developer, comprising (i) an aluminosilicate polymer bearing organic radicals on its surface with functions, selected in the class of SH and xe2x80x94S(CH2)nSxe2x80x94 functions where n is a integer from 1 to 4 inclusive, and (ii) a complexing agent that is released into the photographic developer.